What (if Anything) Did Dorothy Learn?

One of our favorite morality plays ends with a vacuous non-sequitur.

At the end of the 1939 movie version of The Wizard of Oz, Glinda the Good Witch says that Dorothy could have gone home any time, but she had to learn that for herself.  Scarecrow asks Dorothy what she learned.  She replies:  

"Well... I think that it ... That it wasn't enough just to want to see Uncle Henry and Auntie Em.  And it's that if  I ever go looking for my heart's desire again, I won't look any farther than my own back yard because if it isn't there, I never really lost it to begin with."

 Clearly, what begins as a cliche ends as a contradiction.

In addition to Noel Langley, Florence Ryerson, and Edgar Allan Woolf, 15 more writers contributed to the script.  Bert Lahr improvised some dialog; and Ogden Nash also wrote.  This scene is not in the original L. Frank Baum story.  There, having recovered the one silver slipper taken by the Wicked Witch, Dorothy flies home instantly, but drops both silver slippers over the desert.  Historians, economists and numismatists have read much into this yarn, calling it an allegory for the political campaigns of William Jennings Bryan and the question of "free silver" versus a gold standard.  

Be all that as it may, in the context of the film, Dorothy could have encapsulated her experiences in many ways.  She learned that anything truly important is worth overcoming obstacles to achieve.  She learned that while some people are wicked, very many more are not.  Certainly, on the eve of a great war that was obviously about to break out, she learned that small, apparently weak, and seemingly helpless people can defeat evil, if they work together.  She learned that the servants of wicked people are happy to throw off their oppressor. She learned that our limitations are often of our own making: Scarecrow, Lion, and Tin Man each already possessed what they sought.  The first thing she learned was that not all witches are ugly.  

Why did 18 screen writers fail?  It is easy to cite cliches about too many cooks and the committee that designed the horse.  Such folk wisdoms endure because they are so often right.  It is possible that the producers, Mervyn LeRoy and Arthur Freed, feared that any strong statement would ruin the mood of an unintellectual fairy tale.  Speculation may be fruitless.  The fact remains that as a closing statement, Dorothy's summation is best heard once rather than being read closely.

Addendum
The Wonderful Wizard of Oz has been variously reinterpreted, often by historians, economists and numismatists.   Does Scarecrow represent the Farmer, while Tin Man stands for the industrial worker?  See The Wizard of Oz under Numismatics on WashtenawJustice here.

ALSO ON NECESSARY FACTS
The Wizard of Oz and the Anti-Intellectual Tradition 
The Philosophical Breakfast Club 
The Scientific Method 
Scorpio and the Precession of the Equinox 
Do You Know Your Military?
"Soldier's Heart" by Elizabeth Samet